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South African Study Shows J&J’s COVID-19 Vaccine 85% Effective
J&J’s COVID-19 vaccine effectiveness increased over time from 63% at 0-13 days to 84% at 14-27 days, and 85% at one to two months post-boost.
Johnson & Johnson recently announced that its COVID-19 vaccine, Ad26.COV2.S, was 85 percent effective against coronavirus-related hospitalization in a Phase 3b study.
The South African Medical Research Council (SAMRC) conducted the South African 3b Sisnke study, which enrolled healthcare workers across 350 vaccination centers in nine provinces of South Africa.
All participants in the study previously received Ad26.COV2.S as a primary dose.
When caregivers administered a booster shot of the vaccine six to nine months after a primary dose, vaccine effectiveness increased over time, from 63 percent at 0 to 13 days, to 84 percent at 14 to 27 days, and 85 percent at one to two months post-boost.
During the months the study took place, the frequency of the Omicron variant rose from 82 to 98 percent of COVID-19 cases in South Africa.
“This data adds to our growing body of evidence which shows that the effectiveness of the Johnson & Johnson COVID-19 vaccine remains strong and stable over time, including against circulating variants such as Omicron and Delta,” Mathai Mammen, MD, PhD, global head of Janssen research & development, said in the announcement.
A second analysis found that a heterologous booster of the Johnson & Johnson COVID-19 vaccine in individuals who received the Pfizer-BioNTech BNT162b2 mRNA vaccine generated a 41-fold increase in neutralizing antibody responses by four weeks following the boost.
Additionally, patients experienced a 5-fold increase in CD-8+ T-cells to Omicron by two weeks.
A homologous boost with BNT162b2 generated a 17-fold increase in neutralizing antibodies by four weeks following the boost and a 1.4-fold increase in CD8+ T-cells by two weeks.
Researchers noted that the boost in CD8+ T-cells from the Johnson & Johnson vaccine may explain the high efficiency against severe COVID-19 disease and hospitalization, as the Omicron variant has shown to escape neutralizing antibodies.
Glenda E. Gray, MBBCH, FCPaed (SA), president and CEO of the SAMRC, highlighted that aside from the increased infectiousness of Omicron, healthcare workers on the frontlines are already at increased risk of being infected by COVID-19 in the first place.
“We are therefore encouraged to see that boosting with the Johnson & Johnson COVID-19 vaccine regimen provides strong protection in a challenging real-world setting where there is an elevated risk of exposure,” Gray concluded.
